1. Field of the Invention
This invention generally relates to retrieval of downhole in-place or loose apparatus on materials used in the operations of oil and gas wells. More specifically, the invention pertains to an assembly and method which offers the capability for retrieval of fish, such as electric submersible pumps, or the like, for maintenance, rebuilding, and later re-use. Fish is a term commonly used in the oil and gas industry for loose and in-place down-hole items, such as tools, devices or other items which are to be removed from the well.
Though a number of prior art fishing tools can be located, the present invention is designed so as to remove fish from a cased hole where there exists too little clearance between the outer diameter (OD) of the fish and the inner diameter (ID) of the oil well casing. Consequently, there has existed a long-felt unresolved need for a device which will retrieve fish where limited clearance in the oil well casing is a necessary consideration. It is also necessary for the tool to retrieve the fish by an external catch eliminating or minimizing any damage to the fish while still having enough strength and power to pull the fish from the well.
The principal disadvantage of other inventions employed for removing fish from down-hole locations, such as spear-type devices, is that the fish cannot be re-used after removal from the well. In addition, the prior art includes devices which are not capable of functioning where there is limited clearance between the well casing and the fish. Furthermore, some of the devices, including conventional overshots or other external catch retrieval devices, can not lift and remove heavier, difficult to grasp items, such as electric submersible pumps without damage.
2. Related Art
The presently known prior art includes the following: Miller U.S. Pat. No. 1,785,590, McGill U.S. Pat. No. 2,745,693, Crowe U.S. Pat. No. 2,893,491, Lee U.S. Pat. No. 3,108,637, Timmons U.S. Pat. No. 3,380,528, Brown U.S. Pat. No. 3,638,988, Keller U.S. Pat. No. 4,061,389, Taylor U.S. Pat. No. 4,093,294, Taylor U.S. Pat. No. 4,232,894, Taylor U.S. Pat. No. 4,284,137, and Taylor Pat. No. 5,022,473.